Synthesis of sodium zeolite w-z

ABSTRACT

Sodium Zeolite W-Z and a process for making sodium Zeolite W-Z having the chemical formula: 1.0 + OR - 0.1 Na2O.Al2O3. 5.75 + OR - 0.55 SiO2.YH2O wherein Y is a number from 0 to 7 which comprises mixing sodium hydroxide, a source of silica, a source of alumina and water in the following mole ratios: Na2O/SiO2 0.8 to 1.9 SiO2/Al2O3 10.0 to 35.0 H2O/Na2O 100.0 to 160.0 TO OBTAIN A GEL-FORM MIXTURE, DIGESTING THE GEL MIXTURE FOR A PERIOD OF TIME FROM 12 TO 200 HOURS, HEATING THE DIGESTED MIXTURE AT A TEMPERATURE OF FROM 50* TO 150* C. for from 1 to 5 days and recovering sodium Zeolite W-Z. Sodium Zeolite W-Z can be ionexchanged to obtain a crystalline aluminosilicate having catalytic activity for use in hydrocarbon conversion processes.

iJnited States Patent Wang et al.

[54] SYNTHESIS OF SODIUM ZEOLITE W-Z {72] Inventors: Rong W g; JacobMichael Zielonka, both [21] Appl. No.: 817,167

[52] U.S. Cl ..23/113, 252/455 Z [51] Int. Cl. ..Clb 33/28 [58]FieldofSearch ..23/ll1-1l3; 252/455 Z [56] References Cited UNITEDSTATES PATENTS 2,882,244 4/1959 Milton ..23/1l3 3,054,657 9/1962 Breck..23/I13 3,459,501 8/1969 Plank et al. ..23/1 12 OTHER PUBLICATIONSBarret et al., J. Chem. Soc. 1959, Part I, pp. 195-208 JacobsonEncyclopedia of Chemical Reactions Vol. 1, I948,Pg. 48

[ 1 Mar. 14, 1972 Primary Examiner-Edward J. Meros Attorney-James I-I.Laughlin, Jr.

wherein Y is a number from 0 to 7 which comprises mixing sodiumhydroxide, a source of silica, a source of alumina and water in thefollowing mole ratios:

Na O/SiQz 0.8 to 1.9 t0 H O/Na O 100.0 to 160.0

to obtain a gel-form mixture, digesting the gel mixture for a period oftime from 12 to 200 hours, heating the digested miigture at atemperature of from to C. for from I to 5 days and recovering sotfiumZeolite w -ifiodium Zeolite W-Z can be ion-exchanged to obtain acrystalline aluminosilicate having catalytic activity for use inhydrocarbon conversion processes.

4 Claims, No Drawings SYNTHESIS OF SODIUM ZEOLITE W-Z This inventionrelates to a new synthetic crystalline aluminosilicate and to a processfor preparing the same. More particularly, this invention relates to anovel sodium synthetic crystalline aluminosilicate and to a process forpreparing the same wherein silica gel is employed as a reactant.

A number of crystalline aluminosilicates having a structure of rigidthree-dimensional networks characterized by uniform pore openings ofbetween about 6 and about Angstrom units in diameter are known in theart. Each species of crystalline aluminosilicate can be identified byits chemical composition and its unique X-ray powder diffractionpattern. The uniform pore openings permit the entrance of small sizemolecules into the interior of the crystalline aluminosilicates whileexcluding larger size molecules. Accordingly, crystallinealuminosilicates are useful in a number of processes includingseparation of gases by a selective absorption and catalytic conversionsuch as catalytic cracking.

The crystalline aluminosilicates are generally formed by reacting asilica source, an alumina source and an alkali metal source underspecific conditions to form the crystalline product having water ofhydration within the pores thereof. The water of hydration is thenremoved from the crystalline aluminosilicate to form the uniform sizedpores therein. Generally, when it is desired to employ the crystallinealuminosilicates in catalytic conversion processes, such as catalyticcracking, the crystalline aluminosilicate is ion-exchanged to remove thegreat majority of the alkali metal and to substitute therefor catalyticsites such as hydrogen ion or another metal ion such as a rare earthmetal ion. It has been found that crystalline aluminosilicates provideimproved activity and selectivity in catalytic conversion processes ascompared to amorphous silica-alumina catalysts. Furthermore, in orderfor an aluminosilicate to function in a selective absorption process, itmust be in the crystalline form.

Unfortunately it is difficult to predict whether or not a crystallinealuminosilicate can be obtained by merely adjusting reactantcompositions or reaction conditions. As a result there have evolved agreat many processes for producing synthetic crystallinealuminosilicates which minimize or eliminate the production of amorphousproducts. Furthermore, a large number of crystalline aluminosilicatespecies have been produced, each being characterized by a distinctiveX-ray powder diffraction pattern.

The conventional method of preparing crystalline aluminosilicatesinvolves heating a solution of a mixture of oxides of aluminum, siliconand an alkali metal in water at a suitable temperature for a sufficientperiod of time to cause crystallization of the aluminosilicate product.After the product is crystallized out, the desired material is filteredoff, washed with a distilled water until the wash water has a proper pH,and then activated by heating to efiect the desired degree ofdehydration. The composition and structure of the crystallinealuminosilicate which is formed depends upon a number of factorsincluding mole ratio of reactants, the particular reactant employed toprovide the silica and alumina, the conditions of time and temperatureunder which the reaction mixtures are digested to obtain the product,and the particular alkali metal oxides employed.

The production of crystalline Zeolite S is disclosed in U.S. Pat. No.3,054,657 issued Sept. 18, 1962. As disclosed therein, the oxide moleratios of reactants employed fall within the ranges set forth below whenthe source of silica is an aqueous colloidal silica sol:

Na,O/Si0, 0.310 0.0 sio,/A1,o, 6.0m 10.0 11,o/Na,o 20.0 to 100.0

The patent is devoid of any teaching of the use of a reaction mixturecontaining a higher mole ratio of silica to alumina when employing acolloidal silica sol reactant.

U.S. Pat. No. 3,248,170 is also exemplary of the prior art and disclosesthe preparation of a sodium crystalline aluminosilicate from reactionmixtures having the following oxide mole ratio:

Niko/Slo 0.15m 0.6 sio,A1,o, 2.0 m 10.0 H=O/Na,0 30.0 to 200.0

The patentee discloses that when a reaction mixture is maintained withinthe above oxide mole ratio range, a new product identified as sodiumZeolite U is obtained.

it is an object of the present invention to provide a novel crystallinealuminosilicate. It is a further object of the present invention toprovide a method for the preparation of a novel sodium crystallinealuminosilicate. Further objects of the present invention will becomeevident in view of the following detailed discussion.

In accordance with the present invention, it has been discovered that anovel crystalline aluminosilicate which for convenience is identifiedherein as sodium Zeolite W-Z, can be prepared by forming a reactionmixture of sodium hydroxide, a source of alumina, a colloidal silica andwater, the composition of which is expressed in terms of oxide moleratios, is as follows:

N e/s10, 0.8 to 1.9 sio,/A1,o, 10.0 to 35.0 mom-. 0 90.0 to 100.0

The reaction mixture is heat-aged for a certain period until the desiredcrystalline sodium aluminosilicate begins to precipitate therefrom andby suitable means it is then worked up to isolate the crystallinealuminosilicate products.

Chemically, sodium Zeolite W-Z is identified by the following chemicalformula:

1.0: 0.1 Na 0 A1 0 5.75 i 0.55 SiO 0 t0 7 H O In carrying out theprocess of the present invention, sodium hydroxide, colloidal silica, asource of alumina, and water are mixed to obtain the reaction mixture ofthe above-noted compositions. The preferred method for forming thereaction mixture is to add sodium aluminate to sodium hydroxide aqueoussolution and then to add the silica source thereto.

The alumina can be provided by employing sodium aluminate, alumina gel,aluminum metal or aluminum powder as a reactant. As noted above, for thepurposes of the present invention it is desirable to supply the silicacontent by use of an aqueous suspension of colloidal silica. Ludox AMaqueous silica suspension containing 30 percent by weight of colloidalsilica is eminently suitable for the practice of the present invention.

After the reaction mixture is formed, it is aged until the desiredcrystalline aluminosilicate precipitates therefrom. Preferably, aging isconducted in two stages. The first stage being at room temperature andthe second stage being at an elevated temperature. Digestion of thereaction mixture at room temperature can be from a period varying froml2 to 200 hours or preferably from 24 to 72 hours. The precipitate hasthe appearance of a gel ranging in color from cloudy white to colorless.There is also a colorless liquid phase which contains excess water andexcess unused ions not found in precipitated gel. When the reactionmixture has been allowed to digest at room temperature for the desiredlength of time, it is then brought to an elevated temperature for thepurpose of accomplishing the second stage of aging. Aging at elevatedtemperature can be accomplished at a temperature in the range of 50 to150 C., preferably to C. for a period sufficient to allow the formationof the desired crystalline material. Normally, reasonable amounts of thedesired product are formed within 1 to 5 days at the aging temperature.After aging has been accomplished either in one or two steps, theproduct can be separated from the mother liquor of the reaction mixtureby any suitable means such as decantanun-- tion. Preferably the crystalsare then washed in distilled water until the pH of the wash water isabout 9.5 to 10.5 indicating that the crystals are free of excesssodium. The product, after drying at a suitable temperature such as 1001C. can be identified by chemical analysis and by X-ray powderdiffraction patterns.

In Table I below, the product of the present invention, sodium Zeolite WZ is identified by means of its X-ray powder diffraction pattern whichis compared with the X-ray powder diffraction patterns of Zeolite S,natural gmelinite, Barrers species S and sodium Zeolite U. For purposesof measuring the X- ray diffraction pattern, monochromatic copper Kalpha radiation was used with a Guinier-type focusing camera. The peakheights of the radiation (indicated by the symbol: 1) and the intensityof the strongest line or peak (represented by the symbol: l provides thebasis for calculating the relative intensities and the interplanarspacing in Angstrom units (d) corresponding to the lines recorded on thefilm in the X-ray jcamera. The X-ray diffraction patterns differ in manyrespects fthus showing a difference in crystalline structure for each ofithe crystalline aluminosilicates.

Sodium Zeolite W-Z can be ion-exchanged by any method well known in theart to obtain a crystalline aluminosilicate having catalytic activitywhich promotes its use in hydrocarbon conversion processes such ashydrogenation, dehydrogenation, isomerization, reforming, cracking,hydrocracking, polymerization, alkylation and dealkylation whereby ingeneral the hydrocarbon starting material is converted to a higher grademore valuable product.

The following examples illustrates the present invention and are notintended to limit the same.

EXAMPLE I A sodium hydroxide solution was made by adding 30.2 grams ofNaOH to 660 grams deionized water. The solution was stirred until allsolids dissolved. To this solution was added 2.61 grams of Na,0 A1 0. 3HO. The solution was stirred at room temperature for about minutes. Thissolution was then rapidly added to 60 grams of Ludox AM (30 weightpercent SiO The gel mixture was stirred for about one hour (untilhomogeneous). The gel mixture, having a composition in terms of molarratios of oxides of:

TABLE I Natural N a Zeolite W-Z Na. Zeolite U N a Zeolite S Barrerspecies S gmeiinite 100 100 100 100 100 (1 (1/10) d (1/10) d (1110) d(1/10) d (1/10) N oriL-B Broad line.

As is evident from Table 1, sodium Zeolite W-Z differs from Zeolite Sand natural gmelinite since the 7.7 Angstrom line is missing in sodiumZeolite W-Z. Sodium Zeolite W-Z differs from Barrer Species S and sodiumZeolite S since the line at 4.31 Angstroms is missing in Barrier SpeciesS and sodium Zeolite 5. Sodium Zeolite W-Z differs from sodium Zeolite Uby a slight position difference in line 6 and line 9 and intensitydifference in lines 1 and 2. Furthermore, the line 15 with 3.19Angstroms and line 3 with 7.03 Angstroms in sodium Zeolite W-Z aremissing in sodium Zeolite U.

While Zeolite W-Z is obtained by employing reaction systems within theabove-noted ranges, the yield of sodium Zeolite W-Z varies within theseranges. Within the scope of the present invention the following rangesare preferred since the yield of W-Z is greatly increased.

Na,O/Si0, 1.0 to 1.9 Si()=/Al,O l6.0 to 30.0 H,O/Na,0 lO0.0 to 140.0

llllll lOO 0.96 Na O A1 0 6.11 SiO, 4.2 H 0 An X-ray diffractionanalysis characterized the product as about percent sodium Zeolite W-Zhaving the following diffraction pattern wherein dis the interplanarspacing and l is the intensity.

d (observed in A. 1001/1,

Broad Line EXAMPLE 2 A sodium hydroxide solution was made by adding 24grams of NaOH to 700 grams of deionized water. The solution was stirreduntil all solids dissolved. To this solution was added 0.81 gramaluminum powder of particle size less than 100 microns. A semiviolentreaction occurred during which time stirring was stopped until all the Hevolved. Upon the completion of the reaction, the solution was stirredat room temperature for about 30 minutes. This solution was then rapidlyadded to 60 grams of Ludox AM (30 wt. SiO The gel mixture was stirredfor about 1 hour (until homogeneous). The gel mixture, having acomposition in terms of molar ratios of oxides of:

Na,0lSiO, 1.0 SiO,/Al,0, 209

H,OINa,O 140.0

was then digested at room temperature in a sealed vessel for 48 hours.The sample was then agitated and heated in an oven set at 90 C. for 60hours. Upon cooling the crystalline solids were separated from themother liquor by decantation and washed with deionized water until thepH of the wash water became about 10. The solid product was then driedat 95-105 C. for a few hours. An elemental analysis revealed the productto have the following composition:

1.03 Na o A1 5.41 SiO, 3.7 H 0 An X-ray diffraction analysischaracterized the product as about 90 percent sodium Zeolite W-Z havingthe diffraction pattern shown in Example 1.

EXAMPLE 3 A sodium hydroxide solution was made by adding 35.1 grams ofNaOH TO 770 grams deionized water. The solution was stirred until allsolids dissolved. To this solution was added 2.61 grams of Na,0 A1 0 3110. The solution was then rapidly added to 60 grams of Ludox AM (30 wt.SiO The gel mixture was stirred for about one hour (until homogeneous).The gel mixture having a composition in terms of molar ratios of oxidesof:

II II was then digested at room temperature in a sealed vessel for 48hours. The sample was then agitated and heated in an oven set at C. for50 hours. Upon cooling, the crystalline solids were separated from themother liquor on decantation and washed with deionized water until thepH of the wash water became about 10. The solid product was then driedat 95-I05 C. for a few hours. An elemental analysis revealed thefollowing composition:

1.08 Na O A1 0 5.96 Si0 3.3 H 0 An X-ray diffraction analysischaracterized the product as about 90 percent sodium Zeolite W-Z havingthe diffraction pattern shown in Example 1.

EXAMPLE 4 A sodium hydroxide solution was made by adding 31.2 grams NaOHto 950 grams of deionized water. The solution was stirred until allsolids dissolved. To this solution was added 1.88 grams aluminum powderof particle size less than microns. A semiviolent reaction occurredduring which time stirring was stopped until all the H evolved. Upon thecompletion of the reaction, the solution was stirred at room temperaturefor about 30 minutes. This solution was then rapidly added to 60 gramsof Ludox AM (30 wt. SiO The gel mixture was stirred for about 1 hour(until homogeneous). The gel mixture having a composition in terms ofmolar ratios of was then digested at room temperature in a sealed vesselfor 48 hours. The sample was then agitated and heated in an oven at 90C. for 60 hours. Upon cooling, the crystalline solids were separatedfrom the mother liquor by decantation and washed with deionized wateruntil the pH of the wash water became about 10. The solid product wasthen dried at 95-105 C. for a few hours. An elemental analysis revealedthe product to have the following composition:

0.94 Na O A1 0 5.08 SiO, 3.2 11 0 An X-ray diffraction analysischaracterized the product as about 80 percent sodium Zeolite W-Z havingthe diffraction pattern shown in Example 1.

We claim:

1. A process for making sodium Zeolite W-Z having the chemical formula:

1.01:0.1 Na O A1 0; 5.751055 SiO, YH O wherein Y is a number from 0 to 7which comprises mixing sodium hydroxide, a source of silica, a source ofalumina and water in the following mole ratios:

Na,O/Si0, l .0 SiO,/A 1,0, 200 H,O/Na,0 140.0

to obtain a gel-form mixture, digesting the gel mixture for a period oftime of from 12 to 200 hours, heating the digested mixture at atemperature of from 50to C. for from 1 to 5 days and recovering sodiumZeolite W-Z.

2. The process of claim 1 wherein the source of silica is an aqueoussilica suspension.

3. The process of claim 1 wherein the source of alumina is sodiumaluminate.

4. The process of claim 1 wherein the source of alumina is aluminummetal.

t i K t

1.0$NA2O.AL2O3.5.75.0.55 SIO2.YHIO
 2. The process of claim 1 wherein thesource of silica is an aqueous silica suspension.
 3. The process ofclaim 1 wherein the source of alumina is sodium aluminate.
 4. Theprocess of claim 1 wherein the source of alumina is aluminum metal.